This invention relates to sheet material coated with normally tacky and pressure-sensitive adhesives and is particularly concerned with tapes that will be adhered to fabrics or other fibrous substrates and thereafter exposed to moisture which contacts the interface between the adhesive and the substrate.
Normally tacky and pressure-sensitive adhesive tapes represent one of the most versatile families of products ever devised, performing such diverse functions as insulating, mounting, sealing, mending, holding, masking, labeling, binding, joining, protecting, reinforcing, and numerous others. In recent years, various forms of such tapes have been mounted on the plastic outer liner of disposable diapers and used to hold such garments on an infant. The success of this tape closure program has attracted the attention of persons using conventional cloth diapers, but none of the conventional closure tapes has previously proved satisfactory for use on cloth diapers.
One of the major differences between disposable diapers and cloth diapers is the presence of a moisture-impervious polyethylene film on the exterior of the former product. Many conventional pressure-sensitive adhesive tapes readily bond to the smooth polyethylene, remaining firmly adhered in place until such time as the diaper is to be removed from the infant. Cloth diapers, on the other hand, present a quite different situation. Not only must a successful tape closure bond firmly to the irregular, initially dry fibrous surface, but it must also remain firmly adhered when the diaper thereafter becomes saturated, at which time moisture penetrates from the opposite surface of the diaper and comes into contact with the pressure-sensitive adhesive itself. While obtaining initial adhesion to the dry cloth is not especially difficult, maintaining adequate adhesion in the presence of moisture has heretofore proved virtually impossible. The present invention is devoted to the solution of this perplexing problem.